Guide wire

ABSTRACT

A guide wire includes a first wire disposed on the distal side of the guide wire and a second wire disposed on the proximal side. The second wire has an elastic modulus larger than the first wire. The first wire is joined to the second wire at a welded portion by welding. A coil is disposed on the distal side of the first wire. A cover layer is formed on the outer peripheral surface of the wire member in such a manner as to cover at least the welded portion. The cover layer is made from a material capable of reducing the friction of the cover layer, for example, a fluorocarbon resin or a hydrophilic material, to thereby improve the sliding performance of the guide wire. Such a guide wire is excellent in operationality and kink resistance.

This application is a continuation of U.S. application Ser. No.12/463,596 filed on May 11, 2009, which is a divisional of U.S.application Ser. No. 10/634,845 filed on Aug. 6, 2003, the entirecontents of each of which is incorporated by reference herein, andclaims priority to Japanese Patent Application No. 2002-232162 filed onAug. 8, 2002, Japanese Patent Application No. 2002-355909 filed on Dec.6, 2002, and Japanese Patent Application No. 2003-156012 filed on May30, 2003, the entire contents of each of which is incorporated byreference herein.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a guide wire, particularly to a guidewire used to guide a catheter in a body lumen such as a blood vessel.

2. Description of the Related Art

Guide wires are used to guide a catheter in treatment of cites at whichopen surgeries are difficult or which require minimally invasiveness tothe body, for example, PTCA (Percutaneous Transluminal CoronaryAngioplasty), or in examination such as cardio-angiography. A guide wireused in the PTCA procedure is inserted, with the distal end projectingfrom the distal end of a balloon catheter, into the vicinity of a targetangiostenosis portion together with the balloon catheter, and isoperated to guide the distal end portion of the balloon catheter to thetarget angiostenosis portion.

A guide wire used to insert a catheter into a blood vessel complicatedlybent requires appropriate flexibility and restoring performance againstbending, pushability and torque transmission performance (genericallycalled “operationality”) for transmitting an operational force from theproximal end portion to the distal side, and kink resistance (oftencalled “resistance against sharp bending”). To obtain appropriateflexibility as one of the above-described performances, there has beenknown a guide wire configured such that a metal coil having flexibilityis provided around a small-sized core member at the distal end of theguide wire, or a guide wire including a core member made from asuperelastic material such as an Ni—Ti alloy for improving theflexibility and restoring performance.

Conventional guide wires include a core member that is substantiallymade from a single material. In particular, to enhance theoperationality of the guide wire, a material having a relatively highelastic modulus is used as the material of the core member. The guidewire including such a core member, however, has an inconvenience thatthe distal end portion of the guide wire becomes lower in flexibility.On the other hand, if a material having a relatively low elastic modulusis used as the material of the core member for increasing theflexibility of the distal end portion of the guide wire, theoperationality of the proximal end portion of the guide wire isdegraded. In this way, it has been regarded as difficult to satisfy bothrequirements associated with the flexibility and operationality by usinga core member made from a single material.

A guide wire intended to solve such a problem has been disclosed, forexample, in U.S. Pat. No. 5,171,383, wherein a Ni—Ti alloy wire is usedas a core member, and the distal side and the proximal side of the alloywire are heat-treated under different conditions in order to enhance theflexibility of the distal end portion of the alloy wire while enhancingthe rigidity of the proximal side of the alloy wire. Such a guide wire,however, has a problem that the control of the flexibility of the distalend portion by heat-treatment has a limitation. For example, even if itis successful to obtain a sufficient flexibility of the distal endportion of the alloy wire, it may often fail to obtain a sufficientrigidity on the proximal side of the alloy wire.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a guide wire excellentin operationality and kink resistance.

To achieve the above object, according to a first aspect of the presentinvention, there is provided a guide wire including a wire memberincluding a welded portion formed by welding a first wire disposed onthe distal side of the wire body to a second wire disposed on theproximal side from the first wire and made from a material having anelastic modulus larger than that of the first wire, the welded portionbeing made substantially smooth, and a cover layer provided on the outerperiphery of the wire body covering at least the welded portion betweenthe first wire and the second wire.

According to a second aspect of the present invention, there is provideda guide wire including a wire member including a welded portion formedby welding a first wire disposed on the distal side of the wire memberto a second wire disposed on the proximal side from the first wire andmade from a material having an elastic modulus larger than that of thefirst wire, and a cover layer provided on the outer periphery of thewire body in covering at least the welded portion between the first wireand the second wire, wherein the welded portion has a projectionprojecting in the outer peripheral direction.

According to a third aspect of the present invention, there is provideda guide wire including a wire member including a welded portion formedby welding a first wire disposed on the distal side of the wire memberto a second wire disposed on the proximal side from the first wire andmade from a material having an elastic modulus larger than that of thefirst wire, and a cover layer provided on the outer periphery of thewire covering at least the welded portion between the first wire and thesecond wire, and a distal-side cover layer disposed on the distal sidefrom the cover layer, the distal-side cover layer being made from amaterial different from that of the cover layer.

In the above guide wire, preferably, the cover layer is formed in such amanner that the wire body is substantially not heated at the time ofcovering the wire body with the cover layer, and the distal-side coverlayer is formed in such a manner that the wire body is heated at thetime of covering the wire body with the distal-side cover layer.

According to a fourth aspect of the present invention, there is provideda guide wire including a wire member including a welded portion formedby welding a first wire disposed on the distal side of the wire memberto a second wire disposed on the proximal side from the first wire andmade from a material having an elastic modulus larger than that of thefirst wire, and a cover layer provided on the outer periphery of thewire body covering at least the welded portion between the first wireand the second wire, and a proximal-side cover layer disposed on theproximal side from the cover layer, the proximal-side cover layer beingmade from a material different from that of the cover layer.

In the above guide wire, preferably, the cover layer is formed in such amanner that the wire body is substantially not heated at the time ofcovering the wire body with the cover layer, and the proximal-side coverlayer is formed in such a manner that the wire body is heated at thetime of covering the wire body with the proximal-side cover layer.

The distal-side cover layer may be made from a material capable ofreducing the friction of the distal-side cover layer. In particular, thedistal-side cover layer is preferably made from a fluorocarbon resin orhydrophilic material.

The average thickness of the distal-side cover layer is preferably in arange of 1 to 20 μm.

The proximal-side cover layer may be made from a material capable ofreducing the friction of the proximal-side cover layer. In particular,the proximal-side cover layer is preferably made from a fluorocarbonresin or hydrophilic material.

The average thickness of the proximal-side cover layer is preferably ina range of 1 to 20 μm.

The welded portion preferably has a projection projecting in the outerperipheral direction.

The second wire preferably has, in the vicinity of the welded portion, aportion with its cross-sectional area smaller than that of a proximalend portion of the first wire.

The cover layer may be made from a material capable of reducing thefriction of the cover layer. In particular, the cover layer ispreferably made from a fluorocarbon resin or hydrophilic material.

The cover layer is preferably made from a silicone resin. The coverlayer preferably functions as a reinforcing layer for reinforcing thewelded portion.

The cover layer is preferably made from a metal material. The coverlayer is preferably made from a material having rigidity equal to orsmaller than that of a material for forming the first wire.

The average thickness of the cover layer is preferably in a range of 1to 20 μm. The thickness of the cover layer is preferably nearly uniform.

The thickness of a portion, which covers at least the welded portion, ofthe cover layer is preferably nearly uniform.

The cover layer is preferably provided in such a manner as to cross thewelded portion, and to have a thickness nearly uniform from the proximalend to the distal end of the welded portion.

The cover layer is preferably provided in such a manner as to cross theprojection, and to have a thickness nearly uniform from the proximal endto the distal end of the projection.

The wire body preferably has an outer-diameter gradually reducingportion with its outer diameter gradually reduced in the directiontoward the distal end of the wire body.

The guide wire preferably has a spiral coil provided so as to cover atleast a distal end portion of the first wire. The welded portion ispreferably located on the proximal side from the proximal end of thecoil.

The guide wire preferably has a second cover layer provided so as tocover at least part of the coil.

The first wire is preferably made from a superelastic alloy. The secondwire is preferably made from a stainless steel.

The second wire is preferably made from a Co-based alloy. The Co-basedalloy is preferably a Co—Ni—Cr alloy.

A connection end face of the first wire to the second wire and aconnection end face of the second wire to the first wire are preferablyset to be each substantially perpendicular to the axial direction of thefirst and second wires. The welding between the first wire and thesecond wire is preferably performed by a butt resistance weldingprocess.

The projection is preferably formed at the time of welding the firstwire and the second wire to each other.

The guide wire is preferably used in such a manner that the weldedportion is located in a living body.

As described above, since the guide wire of the present invention hasthe first wire disposed on the distal side and the second wire disposedon the proximal side from the first wire and made from a material havingan elastic modulus larger than that of the first wire, it is possible toensure a high rigidity at a proximal end portion while keeping a highflexibility at a distal end portion, and hence to enhance thepushability, torque transmission performance, and trackability of theguide wire.

Since the first wire and the second wire are joined to each other bywelding, it is possible to enhance the joining strength of the joiningportion (welded portion), and hence to certainly transmit a torsionaltorque or pushing force from the second wire to the first wire.

Since the cover layer is provided on the outer periphery of the wirebody in such a manner as to cover at least the welded portion, even ifstepped portions or burrs occur on the outer peripheral surface of thewelded portion, the stepped portions or burrs can be covered with thecover layer. As a result, it is possible to prevent or relieve anadverse effect caused by the stepped portions or burrs.

In the case of providing the cover layer made from a silicone resin, itis possible to ensure a sufficient sliding performance of the entireguide wire while keeping a high joining strength between the first wireand the second wire at the time of forming the cover layer, and hence toenhance the operationality of the guide wire.

In the case of providing the cover layer made from a material capable ofreducing the friction of the cover layer, it is possible to improve thesliding performance of the guide wire in a catheter or the like, andhence to further enhance the operationality of the guide wire. Since thesliding resistance of the guide wire is reduced, it is possible to morecertainly prevent kink (sharp bending) or torsion of the guide wire,particularly, in the vicinity of the welded portion.

In the case of providing the cover layer functioning as a reinforcinglayer'for reinforcing the welded portion, it is possible to furtherenhance the joining strength between the first wire and the second wire.Accordingly, when a torsional torque or pushing force is applied fromthe second wire to the first wire, it is possible to more certainlytransmit the torsional torque or pushing force without deformation orbreakage of the welded portion.

In the case of providing the second cover layer, the distal-side coverlayer, and the proximal-side cover layer, which are different from thecover layer, it is possible to provide a local portion at which thesliding resistance is larger than that of the cover layer, and hence tofacilitate the placement of the guide wire.

Since the projection is formed at the welded portion, it is possible tofurther enhance the joining strength of the joining portion (weldedportion), and hence to more certainly transmit a torsional torque orpushing force from the second wire to the first wire.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other objects, features, and advantages of the presentinvention will become more apparent from the following detaileddescription in conjunction with the accompanying drawings, wherein:

FIG. 1 is a longitudinal sectional view showing a first embodiment of aguide wire of the present invention;

FIGS. 2A to 2D are views showing steps of a procedure for connecting afirst wire and a second wire of the guide wire shown in FIG. 1;

FIG. 3 is a longitudinal sectional view showing a second embodiment ofthe guide wire of the present invention;

FIG. 4 is a longitudinal sectional view showing a third embodiment ofthe guide wire of the present invention;

FIG. 5 is a longitudinal sectional view showing a fourth embodiment ofthe guide wire of the present invention;

FIG. 6 is a longitudinal sectional view showing a modification of aportion, in the vicinity of a welded portion, of the guide wire of thepresent invention;

FIG. 7 is a longitudinal sectional view showing another modification ofthe portion, in the vicinity of a welded portion, of the guide wire ofthe present invention;

FIG. 8 is a typical view illustrating an example of how to use the guidewire of the present invention; and

FIG. 9 is a typical view illustrating the example of how to use theguide wire of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

A guide wire of the present invention will now be described in detail byway of preferred embodiments shown in the accompanying drawings.

FIG. 1 is a longitudinal sectional view of a first embodiment of a guidewire of the present invention, FIGS. 2A to 2D are views showing aprocedure for joining a first wire and a second wire of the guide wireshown in FIG. 1 to each other, and FIG. 3 is a longitudinal sectionalview showing a second embodiment of the guide wire of the presentinvention. For convenience of description, the right side in FIG. 1 andFIGS. 2A to 2D is taken as the “proximal side” and the left side in FIG.1 and FIGS. 2A to 2D is taken as the “distal side”. It is to be notedthat in FIG. 1 and FIGS. 2A to 2D, for easy understanding, the dimensionof the guide wire in the thickness direction is exaggeratedly enlargedwhile the dimension of the guide wire in the length direction isshortened, and therefore, the ratio of the thickness to the length issignificantly different from the actual ratio. The same is true forFIGS. 3 to 5 to be described later.

A guide wire 1 shown in FIG. 1 is of a type used to be inserted in acatheter, and includes a wire member 10 and a spiral coil 4. The wiremember 10 is formed by joining a first wire 2 disposed on the distalside to a second wire 3 disposed on the proximal side from the firstwire 2. The entire length of the guide wire 1 is not particularlylimited but is preferably in a range of about 200 to 5,000 mm. The outerdiameter of a constant outer-diameter portion of the wire member 10 isnot particularly limited but is preferably in a range of about 0.2 to1.2 mm.

The first wire 2 is configured as a wire having elasticity. The lengthof the first wire 2 is not particularly limited but is preferably in arange of about 20 to 1,000 mm.

According to this embodiment, the first wire 2 has an outer-diameterconstant portion extending for a specific length from the proximal end,and an outer-diameter gradually reducing portion 15 extending from theouter-diameter constant portion to the distal end. The outer-diameter ofthe outer-diameter gradually reducing portion 15 is gradually reduced inthe direction toward the distal end. The provision of the outer-diametergradually reducing portion 15 is effective to gradually reduce therigidity (flexural rigidity, torsional rigidity) of the first wire 2 inthe direction toward the distal end. As a result, the distal end portionof the guide wire 1 has a high flexibility, to improve trackability andsafety to a blood vessel and to prevent sharp-bending and the like.

In the configuration shown in the figure, the outer-diameter graduallyreducing portion 15 is formed as part of the first wire 2; however, sucha portion 15 may be formed as the whole of the first wire 2. The taperangle (reduction ratio of the outer-diameter) of the outer-diametergradually reducing portion 15 may be constant or partially changed inthe longitudinal direction of the first wire 2. For example, portions ineach of which the taper angle (reduction ratio of the outer diameter) isrelatively large and portions in each of which the taper angle isrelatively small may be alternately repeated by a plurality of numbers.

The first wire 2 may be configured such that a portion with its outerdiameter is kept constant in the longitudinal direction be located at amiddle portion of the outer-diameter gradually reducing portion 15 or onthe distal side from the outer-diameter gradually reducing portion 15.For example, the first wire 2 may be configured such that a plurality oftaper portions in each of which the outer diameter is gradually reducedin the direction toward the distal end be formed in the longitudinaldirection and a portion in which the outer diameter is kept constant inthe longitudinal direction be formed between adjacent two of the taperportions. The first wire 2 having such a configuration can exhibit thesame effect as that described above.

Unlike the configuration shown in the figure, the proximal end of theouter-diameter gradually reducing portion 15 may be located at a middlepoint of the second wire 3, and more specifically, the outer-diametergradually reducing portion 15 may be formed so as to cross the boundary(welded portion 14 to be described later) between the first wire 2 andthe second wire 3.

The material for forming the first wire 2 is not particularly limitedbut may be selected from metal materials such as stainless steels. Inparticular, alloys having pseudo-elasticity (for example, superelasticalloys) are preferable, and superelastic alloys are more preferable.Superelastic alloys are relatively flexible, good in restoringperformance, and less susceptible to reforming. Accordingly, if thefirst wire 2 is made from a superelastic alloy, the guide wire 1including such a first wire 2 has, at its distal portion, a highflexibility and a high restoring performance against bending, and a hightrackability to a blood vessel complicatedly curved or bent, to therebyenhance the operationality of the guide wire 1. Even if the first wire 2is repeatedly deformed, that is, curved or bent, the first wire 2 is noor less plastic deforming because of its high restoring performance.This prevents degradation of the operationality due to the plasticdeforming of the first wire 2 during use of the guide wire 1.

Pseudo-elastic alloys include those of a type in which the stress-straincurve in a tensile test has any shape, those of a type in which atransformation point such as As, Af, Ms, or Mf can be significantlymeasured or not measured, and those of all types in which the shape isgreatly deformed by stress and then restored nearly to an original shapeby removal of stress.

Examples of superelastic alloys include Ni—Ti alloys such as an Ni—Tialloy containing Ni in an amount of 49-52 atomic %, a Cu—Zn alloycontaining Zn in an amount of 38.5 to 41.5 wt %, a Cu—Zn—X alloycontaining X in an amount of 1 to 10 wt % (X: at least one kind selectedfrom a group consisting of Be, Si, Sn, Al, and Ga), and an Ni—Al alloycontaining Al in an amount of 36 to 38 atomic %. Of these materials, theNi—Ti alloy is preferable. In addition, a superelastic alloy representedby a Ni—Ti alloy is excellent in adhesion against a cover layer 5 or asecond cover layer 6.

The distal end of the second wire 3 is joined to the proximal end of thefirst wire 2 at a welded portion 14 by welding. The second wire 3 is awire member having elasticity. The length of the second wire 3 is notparticularly limited but may be in a range of about 20 to 4,800 mm.

The second wire 3 is made from a material having an elastic modulus(Young's modulus or modulus of longitudinal elasticity, modulus ofrigidity or modulus of transverse elasticity, or bulk modulus) largerthan that of the first wire 2. The second wire 3 can thus exhibit anappropriate rigidity (flexural rigidity, torsional rigidity). As aresult, the guide wire 1 becomes firm, to improve the pushability andtorque transmission performance, thereby enhancing the operationality atthe time of insertion of the guide wire 1.

The material for forming the second wire 3 is not particularly limitedbut may be selected from metal materials, for example, stainless steels(all kinds specified in SUS, for example, SUS304, SUS303, SUS316,SUS316L, SUS316J1, SUS316J1L, SUS405, SUS430, SUS434, SUS444, SUS429,SUS430F, and SUS302), piano wire steels, cobalt alloys, and alloyshaving pseudo-elasticity.

In particular, cobalt alloys are preferably used for the second wire 3.This is because the second wire 3 made from a cobalt alloy has a highelastic modulus and an appropriate elastic limit. Such a second wire 3exhibits a good torque transmission performance, thereby hardly causinga problem associated with buckling or the like. Any type of cobalt alloymay be used insofar as it contains Cobalt. In particular, a cobalt alloycontaining cobalt as a main component (that is, a cobalt-based alloycontaining cobalt in an amount [in wt %] being the largest among thecontents of all components of the alloy) is preferably used, andfurther, a Co—Ni—Cr alloy is more preferable. The use of the cobaltalloy having such a composition as the material for forming the secondwire 3 is effective to further enhance the above-described effects. Thecobalt alloy having such a composition is also advantageous in thatsince the alloy exhibits plasticity in deformation at room temperature,the second wire 3 made from such a cobalt alloy is easily deformableinto a desired shape, for example, during use of the guide wire. Afurther advantage of the cobalt alloy having such a composition is asfollows: namely, since the second wire 3 made from such a cobalt alloyhas a high elastic modulus and is cold-formable even if it exhibits ahigh elastic limit, the second wire 3 can be thinned while sufficientlypreventing occurrence of buckling, and therefore, can exhibit a highflexibility and a high rigidity enough to be inserted into a desiredsite.

The Co—Ni—Cr alloy is exemplified by an alloy containing 28-50 wt % ofCo, 10-30 wt % of Ni, and 10-30 wt % of Cr, the balance being Fe. Inthis alloy, part of any component may be substituted by another element(substitution element). The incorporation of such a substitution elementexhibits an effect inherent to the kind thereof. For example, theincorporation of at least one kind selected from a group consisting ofTi, Nb, Ta, Be, and Mo further improves the strength of the second wire3. In the case of incorporating one or more substitution elements otherthan Co, Ni, and Cr, the total content of the substitution elements ispreferably in a range of 30 wt % or less.

For example, part of Ni may be substituted by Mn, which is effective tofurther improve the workability. Part of Cr may be substituted by Moand/or W, which is effective to further improve the elastic limit. Ofthe Co—Ni—Cr alloys, a Co—Ni—Cr—Mo alloy is particularly preferable.

Examples of compositions of the Co—Ni—Cr alloys include (1) 40 wt %Co-22wt % Ni-25 wt % Cr-2 wt % Mn-0.17 wt % C-0.03 wt % Be—Fe (balance),(2) 40 wt % Co-15 wt % Ni-20 wt % Cr-2 wt % Mn-7 wt % Mo-0.15 wt %C-0.03 wt % Be—Fe (balance), (3) 42 wt % Co-13 wt % Ni-20 wt % Cr-1.6 wt% Mn-2 wt % Mo-2.8 wt % W-0.2 wt % C-0.04 wt % Be—Fe (balance), (4) 45wt % Co-21 wt % Ni-18 wt % Cr-1 wt % Mn-4 wt % Mo-1 wt % Ti-0.02 wt %C-0.3 wt % Be—Fe (balance), and (5) 34 wt % Co-21 wt % Ni-14 wt % Cr-0.5wt % Mn-6 wt % Mo-2.5 wt % Nb-0.5 wt % Ta—Fe (balance). The wording“Co—Ni—Cr alloy” used herein is the conception including these Co—Ni—Cralloys.

If a stainless steel is used as the material for forming the second wire3, the pushability and torque transmission performance can be furtherenhanced.

The first wire 2 and the second wire 3 may be made from differentalloys, and particularly, the first wire 2 is preferably made from amaterial having an elastic modulus smaller than that of the material ofthe second wire 3. With this configuration, the distal end portion ofthe guide wire 1 has a high flexibility, and the proximal end portion ofthe guide wire 1 has a high rigidity (flexural rigidity, torsionalrigidity). As a result, the guide wire 1 has a high pushability and ahigh torque transmission performance, thereby enhancing theoperationality, and also exhibits, on the distal side, a highflexibility and a high restoring performance, thereby improvingtrackability and safety to a blood vessel.

As one preferred combination of materials of the first wire 2 and thesecond wire 3, the first wire 2 is made from a superelastic alloy andthe second wire 3 is made from a Co—Ni—Cr alloy or a stainless steel.With this configuration, the above-described effects become moresignificant.

In the configuration shown FIG. 1, the second wire 3 has a nearlyconstant outer diameter over the entire length; however, the second wire3 may have portions with outer diameters changed in the longitudinaldirection.

From the viewpoint of enhancing the flexibility and restoringperformance of the distal end portion of the first wire 2, it ispreferred to use a Ni—Ti alloy as the superelastic alloy for forming thefirst wire 2.

The coil 4 is a member formed by spirally winding a wire, especiallyfine filamentous wire, and is provided so as to cover the distal endportion of the first wire 2. In the configuration shown in FIG. 1, thedistal end portion of the first wire 2 is disposed in an approximatelyaxially center portion of the coil 4 in such a manner as to be not incontact with the inner surface of the coil 4. In addition, the weldedportion 4 is located on the proximal side from the proximal end of thecoil 4.

It is to be noted that in the configuration shown in FIG. 1, the coil 4is loosely disposed in such a manner that a slight gap remains betweenadjacent spirally wound wire portions in a state that no external forceis applied to the coil 4; however, the coil 4 may be tightly disposed insuch a manner that no gap remains between the adjacent spirally woundwire portions in a state that no external force is applied to the coil4.

The coil 4 may be made from a metal material such as a stainless steel,a superelastic alloy, a cobalt alloy, a noble metal such as gold,platinum, or tungsten, or an alloy containing such a noble metal. Inparticular, the coil 4 is preferably made from a radiopaque materialsuch as a noble metal. If the coil 4 is made from such a radiopaquematerial, the guide wire 1 can exhibit an X-ray contrast performance.This makes it possible to insert the guide wire 1 in a living body whileconfirming the position of the distal end portion of the guide wire 1under fluoroscopy. The distal side and proximal side of the coil 4 maybe made from different alloys. For example, the distal side of the coil4 may be formed of a coil made from a radiopaque material and theproximal side of the coil 4 be formed of a coil made from a relativelyradiolucent material such as a stainless material. The entire length ofthe coil 4 is not particularly limited but may be in a range of about 5to 500 mm.

The proximal end portion and the distal end portion of the coil 4 arefixed to the first wire 2 by a fixing material 11 and a fixing material12, respectively, and an intermediate portion (close to the distal end)of the coil 4 is fixed to the first wire 2 by a fixing material 13. Eachof the fixing materials 11, 12, and 13 is a solder (brazing material).Alternatively, each of the fixing materials 11, 12, and 13 may be anadhesive. In addition, in place of using the fixing material, the coil 4may be fixed to the first wire 2 by welding. To prevent damage of theinner wall of a blood vessel, the leading end surface of the fixingmaterial 12 is preferably rounded.

According to this embodiment, since the first wire 2 is partiallycovered with the coil 4, the contact area of the first wire 2 with theinner wall of a catheter used together with the guide wire 1 is small,with a result that it is possible to reduce the sliding resistance ofthe guide wire 1 in the catheter. This is effective to further improvethe operationality of the guide wire 1.

In this embodiment, the wire having a circular shape in cross-section isused for the coil 4; however, the cross-sectional shape of the wire usedfor the coil 4 may be another shape such as an elliptic shape or aquadrilateral shape (especially, rectangular shape).

In the guide wire 1, the first wire 2 and the second wire 2 are joinedto each other by welding. The welded portion (joining portion) 14between the first wire 2 and the second wire 3 has a high joiningstrength, to allow a torsional torque or pushing force to be certainlytransmitted from the second wire 3 to the first wire 2.

The outer peripheral portion of the welded portion 14 is preferably madesubstantially smooth, for example, in accordance with steps 3 and 4 of aprocedure of joining the first wire 1 to the second wire 2 by welding(to be described later).

In this embodiment, a connection end face 21 of the first wire 2 to thesecond wire 3 and a connection end face 31 of the second wire 3 to thefirst wire 2 are each formed into a plane nearly perpendicular to theaxial (longitudinal) direction of both the wires 2 and 3. Thissignificantly facilitates working for forming the connection end faces21 and 31, to achieve the above-described effects without complicatingthe steps for producing the guide wire 1.

It is to be noted that each of the connection end faces 21 and 31 may betilted relative to the plane perpendicular to the axial (longitudinal)direction of both the wires 2 and 3, or formed into a recessed or raisedshape.

The method of welding the first wire 2 and the second wire 3 to eachother is not particularly limited but is generally exemplified by spotwelding using laser or butt resistance welding such as butt seamwelding. In particular, to ensure a high joining strength of the weldedportion 14, butt resistance welding is preferable.

The procedure of joining the first wire 2 and the second wire 3 to eachother by butt seam welding as one example of butt resistance weldingwill be described with reference to FIGS. 2A to 2D. FIGS. 2A to 2D showsteps 1 to 4 of the procedure of joining the first wire 2 and the secondwire 3 to each other by butt seam welding.

In the step 1, the first wire 2 and the second wire 3 are fixed(mounted) to a butt welder (not shown).

In the step 2, the connection end face 21 on the proximal side of thefirst wire 2 and the connection end face 31 on the distal side of thesecond wire 3 are butted to each other while a specific voltage isapplied thereto by the butt welder. With this operation, a fused layer(welded surface) is formed at the contact portion, whereby the firstwire 2 and the second wire 3 are strongly joined to each other.

In the step 3, a projection of the joining portion (welded portion 14),formed by deformation of the joining portion upon butt welding, isremoved, with a result that the outer periphery of the welded portion 14is made substantially smooth. The removal of the projection may beperformed by polishing, grinding, or chemical treatment such as etching.

In the step 4, a portion, on the distal side from the joining portion(welded portion 14), of the first wire 2 is polished or ground, to formthe outer-diameter gradually reducing portion 15 with its outer diametergradually reduced in the direction toward the distal end.

If the proximal end of the outer-diameter gradually reducing portion 15is set on the proximal side from the welded portion 14, the proceduremay be jumped from the step 2 to the step 4, with the step 3 omitted.

The wire member 10 has a cover layer 5 that covers the whole or part ofthe outer surface (outer peripheral surface). The cover layer 5 can beformed for satisfying various purposes, one of which is to reduce thefriction (sliding resistance) of the guide wire 1 for improving thesliding performance of the guide wire 1, thereby enhancing theoperationality of the guide wire 1.

To satisfy the above-described purpose, the cover layer 5 is preferablymade from a material capable of reducing the friction of the guide wire1. With this configuration, since the friction resistance (slidingresistance) of the guide wire 1 against the inner wall of a catheterused together with the guide wire 1 is reduced, the sliding performanceof the guide wire 1 is improved, to enhance the operationality of theguide wire 1 in the catheter. Further, since the sliding resistance ofthe guide wire 1 is reduced, it is possible to more certainly prevent,at the time of movement and/or rotation of the guide wire 1 in thecatheter, kink (sharp bending) or torsion of the guide wire 1,particularly, in the vicinity of a welded portion of the guide wire 1.

Examples of the materials capable of reducing the friction of the guidewire 1 include polyolefins such as polyethylene and polypropylene,polyvinyl chloride, polyesters (such as PET and PBT), polyamide,polyimide, polyurethane, polystyrene, polycarbonate, silicone resins,fluorocarbon resins (such as PTFE and ETFE), and composite materialsthereof.

In particular, the use of a fluorocarbon resin or a composite materialthereof as the material for forming the cover layer 5 is advantageous ineffectively reducing the friction resistance (sliding resistance) of theguide wire 1 having such a cover layer 5 against the inner wall of acatheter, to improve the sliding performance, thereby enhancing theoperationality of the guide wire 1 in the catheter. Further, in the caseof moving and/or rotating the guide wire 1 having such a cover layer 5in the catheter, it is possible to more certainly prevent kink (sharpbending) or torsion of the guide wire, particularly, in the vicinity ofthe welded portion 14.

The formation of the cover layer 5 using a fluorocarbon resin or acomposite material thereof is generally performed by heating thefluorocarbon rosin and covering the wire member 10 with the fluorocarbonresin, for example, in accordance with a baking process or sprayingprocess. Such a covering process is effective to significantly enhancethe adhesion of the cover layer 5 with the wire member 10.

In the case of using a silicone resin or a composite material thereof asthe material for forming the cover layer 5, it is possible to form thecover layer 5 certainly, strongly adhering on the wire member 10 withoutthe need of heating the silicone resin. To be more specific, by using asilicone resin of a reaction-curing type or a composite materialthereof, the formation of the cover layer 5 can be performed at roomtemperature. The formation of the cover layer 5 at room temperature isadvantageous not only in realizing simple coating but also sufficientlykeeping the joining strength of the welded portion 14between the firstwire 2 and the second wire 3 without thermal degradation of the weldedportion 14.

A hydrophilic material or a hydrophobic material can be also used asanother preferred example of the material capable of reducing thefriction of the guide wire 1. In particular, the hydrophilic material ispreferable.

Examples of the hydrophilic materials include a cellulose based polymer,a polyethylene oxide based polymer, a maleic anhydride based polymer(for example, a maleic anhydride copolymer such asmethylvinylether-maleic anhydride copolymer), an acrylic amide basedpolymer (for example, polyacrylic amide or polyglycidylmethacrylate-dimethyl acrylic amide [PGMA-DMAA] block copolymer),water-soluble nylon, polyvinyl alcohol, and polyvinyl pyrolidone.

In many cases, the hydrophilic material can exhibit a lubricatingperformance in a wet (water-absorbing) state. The use of the covermember 5 made from such a hydrophilic material is effective to reducethe friction resistance (sliding resistance) of the guide wire 1 againstthe inner wall of a catheter used together with the guide wire 1, toimprove the sliding performance of the guide wire 1, thereby enhancingthe operationality of the guide wire 1 in the catheter.

The cover layer 5 may be formed in such a manner as to cover the wholeor part of the wire member 10 in the longitudinal direction. Inparticular, the cover layer 5 is preferably formed so as to cover thewelded portion 14, and specifically, formed in a region including thewelded portion 14. With this configuration, even if stepped portions orburrs may occur on the outer peripheral portion of the welded portion14, such stepped portions or burrs are covered with the covered layer 5,whereby a sufficient sliding performance can be ensured. Also, since thecover layer 5 has a nearly uniform outer diameter, the slidingperformance can be further improved.

The thickness (in average) of the cover layer 5 is not particularlylimited but is preferably in a range of about 1 to 20 μm, morepreferably, about 2 to 10 μm. If the thickness of the cover layer 5 isless than the lower limit, the effect obtained by formation of the coverlayer 5 may be not sufficiently achieved and the cover layer 5 may beoften peeled. If the thickness of the cover layer 5 is more than theupper limit, the physical properties of the wire may be obstructed andthe cover layer 5 may be often peeled.

According to the present invention, the outer peripheral surface of thewire member 10 may be subjected to a treatment (such as chemicaltreatment or heat treatment) for improving the adhesion characteristicof the cover layer 5, or may be provided with an intermediate layer forimproving the adhesion characteristic of the cover layer 5.

A second embodiment of the guide wire of the present invention will bedescribed with reference to FIG. 3, principally, about differences fromthe first embodiment, with the description of the same features omitted.

A guide wire 1 shown in FIG. 3 is configured such that the distal end ofa cover layer 5 is located on the proximal side from the proximal end ofa coil 4, and a second cover layer 6 different from the cover layer 5 isformed on the distal side from the cover layer 5.

The second cover layer 6 is provided so as to cover the whole or part ofthe coil 4. In the configuration shown in the figure, the second coverlayer 6 covers the whole of the coil 4.

The second cover layer 6 may be made from a material selected from theabove-described materials used for forming the cover layer 5 and othermaterials, for example, polyolefins such as polyethylene andpolypropylene, polyvinyl chloride, polyesters (such as PET and PBT),polyamide, polyimide, polyurethane, polystyrene, polycarbonate,fluorocarbon resins, silicone resins, silicone rubbers, and variouskinds of elastomers (for example, thermoplastic elastomers such aspolyamide-based elastomer and polyester-based elastomer). The materialfor forming the second cover layer 6 may be identical to or differentfrom the material for forming the cover layer 5.

The materials for forming the cover layer 5 and the second cover layer 6are not particularly limited as described above, but are preferably setsuch that a silicone resin or a composite material be used for formingthe cover layer 5 and a fluorocarbon resin or a composite materialthereof be used for forming the second cover layer 6.

With this configuration, it is possible to combine the above-describedadvantage obtained by the use of a silicone resin with an advantageobtained by the use of a fluorocarbon resin. Concretely, by adoptingsuch a combination of the materials of the cover layer 5 and the secondcover layer 6, it is possible to obtain a sufficient sliding performanceof the entire guide wire 1 while keeping the joining strength of thewelded portion 14 between the first wire 2 and the second wire 3, andhence to enhance the operationality of the guide wire 1.

In the case of using a silicone resin or a composite material thereoffor forming the cover layer 5 and also using a fluorocarbon resin or acomposite material for forming the second cover layer 6, it is preferredthat the wire member 10 be not heated for forming the cover layer 5 asdescribed above and be heated for forming the second cover layer 6. Withthis configuration, it is possible to make the above-described effectsignificant and to enhance the adhesion of the second cover layer 6 withthe wire member 10.

In the case of using a hydrophobic resin for forming the cover layer 5and also using a hydrophilic resin for forming the second cover layer 6,it is possible to improve the sliding performance in a catheter and toenhance crossability in a blood vessel.

The thickness (in average) of the second cover layer 6 is notparticularly limited but is preferably in a range of about 1 to 20 μm,more preferably, about 2 to 10 μm. The thickness of the second coverlayer 6 may be identical to or different from that of the cover layer 5.

The guide wire of the present invention may be not provided with thecoil 4. In this case, the second cover layer 6 may be provided or notprovided at the position where the coil 4 is omitted.

In the configuration shown in FIG. 3, the distal end of the cover layer5 is joined to the proximal end of the second cover layer 6, and istherefore continuous thereto; however, the distal end of the cover layer5 may be separated from the proximal end of the second cover layer 6, orthe cover layer 5 may be partially overlapped to the second cover layer6.

FIG. 4 is a longitudinal sectional view showing a third embodiment ofthe guide wire of the present invention. The third embodiment of theguide wire of the present invention will be described with reference toFIG. 4, principally, about differences from the previous embodiments,with the description of the same features omitted.

According to a guide wire 1 in this embodiment, a first wire 2 has anouter-diameter gradually reducing portion 15 and an outer-diametergradually reducing portion 16 provided on the proximal side from theouter-diameter gradually reducing portion 15. In this way, the firstwire 2 (or second wire 3) may have outer-diameter gradually reducingportions at a plurality of positions.

According to the guide wire 1 in this embodiment, the second wire 3 hasan outer-diameter gradually reducing portion 18 in the vicinity of thedistal end thereof. To be more specific, the second wire 3 has a firstportion provided in the vicinity of the distal end and a second portionprovided on the proximal side from the first portion, wherein the secondportion has rigidity higher than that of the first portion. This givesrise to an effect of making transition of elasticity between the firstwire 2 and the second wire 3 smooth.

In this embodiment, a welded portion 14 has a projection 17 projectingin the outer peripheral direction. The formation of such a projection 17is effective to enlarge a joining area between the first wire 2 and thesecond wire 3, and hence to significantly enhance the joining strength.This is advantageous in more certainly transmitting a torsional torqueor pushing force from the second wire 3 to the first wire 2.

The formation of the projection 17 may make the welded portion 14between the first wire 2 and the second wire 3 easily visible underfluoroscopy. As a result, it is possible to easily, certainly recognizethe advancing state of the guide wire 1 and a catheter in a blood vesselor the like by checking the fluoroscopic image, and hence to shorten theoperation time and to improve the safety.

The height of the projection 17 is not particularly limited but ispreferably in a range of 0.001 to 0.3 mm, more preferably, 0.005 to 0.05mm. If the height of the projection 17 is less than the lower limit, itmay fail to sufficiently obtain the above-described effects depending onthe materials of the first wire 2 and the second wire 3. If the heightof the projection 17 is more than the upper limit, since the innerdiameter of a lumen, in which the guide wire 1 is to be inserted, of aballoon catheter is fixed, the outer diameter of the second wire 3 onthe proximal side must be thin relative to the height of the projection17, with a result that it may become difficult to ensure sufficientphysical properties of the second wire 3.

The projection 17 can be formed by smoothly shaping the projection inthe step 3 of the above-described procedure of joining the first wire 2to the second wire 3 (see FIG. 2). In particular, in the case where thesecond wire 2 has the outer-diameter gradually reducing portion (smallcross-sectional area portion) 18 as in the guide wire 1 according tothis embodiment, the projection 17 can be formed by welding the firstwire 2 to the second wire 3 having a cross-sectional area graduallyreducing (small cross-sectional area portion) with its cross-sectionalarea gradually reduced in the direction toward the distal end by theabove-described procedure.

A cover layer 5 covers the outer-diameter gradually reducing portion 18and the projection 17 and has a substantially uniform outer diameter.The term “substantially uniform outer diameter” contains an outerdiameter smoothly changed within such a range as not to cause anyinconvenience in use of the guide wire.

In this embodiment, the cover layer 5 covers a region including the coil4, the first wire 2, and the second wire 3; however, the cover layer 5may be formed so as to cover the first wire 2 and the second wire 3, andthe coil 4 be covered with a material different from the cover layer 5,for example, a hydrophilic material.

FIG. 5 is a longitudinal sectional view showing a fourth embodiment ofthe guide wire of the present invention. The fourth embodiment of theguide wire of the present invention will be described with reference toFIG. 5, principally, about differences from the previous embodiments,with the description of the same features omitted.

According to a guide wire 1 in this embodiment, a cover layer 5 isformed so as to cover the vicinity of a welded portion 14 of a wiremember 10, a distal-side cover layer 6′ different from the cover layer 5is formed on the distal side from the cover layer 5, and a proximal-sidecover layer 7 different from the cover layer 5 is formed on the proximalside from the cover layer 5.

The distal-side cover layer 6′ may be made from a material selected fromthe materials used for forming the cover layer 5 and the second coverlayer 6 in the previous embodiments. The material for forming thedistal-side cover layer 6′ may be identical to or different from that ofeach of the cover layer 5 and the proximal-side cover layer 7.

The material of the proximal-side cover layer 7 is not particularlylimited but maybe selected from the materials used for forming the coverlayer 5 and the distal-side cover layer 6′ and other materials. Thematerial of the proximal-side cover layer 7 maybe identical to ordifferent from the material used for forming each of the cover layer 5and the distal-side cover layer 6′.

The proximal-side cover layer 7 may be made from any material asdescribed above, but is preferably made from a fluorocarbon resin or acomposite material thereof. This makes it possible to effectively reducethe friction resistance (sliding resistance) of the guide wire 1 againstthe inner wall of a catheter and improve the sliding performance, andhence to enhance the operationality of the guide wire 1 in the catheter.Further, in the case of moving and/or rotating the guide wire 1 in thecatheter, it is possible to more certainly prevent kink (sharp bending)or torsion of the guide wire 1, particularly, in the vicinity of thewelded portion.

The materials of the cover layer 5, the distal-side cover layer 6′, andthe proximal-side cover layer 7 are preferably set such that the coverlayer 5 be made from a silicone resin or a composite material thereof,the distal-side cover layer 6′ be made from a fluorocarbon resin or acomposite material thereof, and the proximal-side cover layer 7 be madefrom a fluorocarbon resin or a composite material thereof.

With this configuration, it is possible to combine the above-describedadvantage obtained by the use of a silicone resin with theabove-described advantage obtained by the use of a fluorocarbon resin.Concretely, by adopting such a combination of the materials of the coverlayer 5, the distal-side cover layer 6′, and the proximal-side coverlayer 7, it is possible to obtain a sufficient sliding performance ofthe entire guide wire 1 while keeping the joining strength of the weldedportion 14 between the first wire 2 and the second wire 3, and hence toenhance the operationality of the guide wire 1.

In the case of using the above-described combination of the materialsfor forming the cover layer 5, the distal-side cover layer 6′, and theproximal-side cover layer 7, as described above, it is preferred thatthe wire member 10 be not heated for forming the cover layer 5 and beheated for forming each of the distal-side cover layer 6′ and theproximal-side cover layer 7. With this configuration, it is possible tomake the above-described effect significant and to enhance the adhesionof each of the distal-side cover layer 6′ and the proximal-side coverlayer 7 on the wire member 10.

The thickness (in average) of the distal-side cover layer 6′ is notparticularly limited but is preferably in a range of about 1 to 20 μm,more preferably, about 2 to 10 μm. The thickness of the distal-sidecover layer 6′ may be identical to or different from each of thethickness of the cover layer 5 and the thickness of the proximal-sidecover layer 7.

The thickness (in average) of the proximal-side cover layer 7 is notparticularly limited but is preferably in a range of about 1 to 20 μm,more preferably, about 2 to 10 μm. The thickness of the proximal-sidecover layer 7 may be identical to or different from each of thethickness of the cover layer 5 and the thickness of the distal-sidecover layer 6′.

In the configuration shown in FIG. 5, the proximal end of the coverlayer 5 is joined to the distal end of the proximal-side cover layer 7,and is therefore continuous thereto; the proximal end of the cover layer5 may be separated from the distal end of the proximal-side cover layer7, or the cover layer 5 may be partially overlapped to the proximal-sidecover layer 7.

In this embodiment, the distal-side cover layer 6′ covers the coil 4;however, the coil 4 may be covered with a different material, forexample, a hydrophilic material.

FIGS. 6 and 7 are longitudinal sectional views showing modifications ofa portion, in the vicinity of the welded portion, of the guide wire ofthe present invention.

As shown in FIG. 6, a cover layer 5′ is formed on the outer periphery ofa portion, in the vicinity of a welded portion 14, of a wire member 10in such a manner as to cover the outer periphery of the welded portion14, that is, to cross the welded portion 14. Like the above-describedconfiguration, a distal-side cover layer 6′ and a proximal-side coverlayer 7 are formed on the distal side and the proximal side from thecover layer 5′, respectively. In this case, the thickness of the coverlayer 5′ is nearly uniform in the axial direction.

The cover layer 5′ functions as a reinforcing layer for reinforcing thewelded portion 14. The provision of such a cover layer 5′ is effectiveto improve the welding strength of the welded portion 14. As a result,in the case of applying a torsional torque or a pushing force from thesecond wire 3 to the first wire 2, it is possible to prevent deformationand breakage of the welded portion 14, and hence to more certainlytransmit the torsional torque or pushing force.

The cover layer 5′ may be made from a material selected from metalmaterials and resin materials. In particular, a metal material ispreferably used.

The cover layer 5′ is preferably made from a material having a rigidityequal to or smaller than that of the above-described material forforming the first wire 2, that is, having a flexibility equal to orlarger than that of the material for forming the first wire 2. With thisconfiguration, it is possible to obtain the advantage by theabove-described reinforcing effect while sufficiently ensuring theflexibility and restoring performance against bending in the vicinity ofthe welded portion 14.

A projection 17 projecting in the outer peripheral direction is formedon a welded portion 14 shown in FIG. 7. The effect obtained by formationof the projection 17, and the condition and forming method of theprojection 17 may be the same as those described above.

A cover layer 5 similar to that described above is provided on the outerperiphery of a wire member 10. In this case, the cover layer 5 is formedso as to cross the projection 17, that is, cross the welded portion 14.The thickness of the cover layer 5 is nearly uniform from the proximalend to the distal end of the projection 17. With this configuration, itis possible to sufficiently ensure the flexibility and restoringperformance against bending in the vicinity of the welded portion 14.

In the configuration shown in FIGS. 4, 5, and 7, each of one side (upperside in the figure) and the other side (lower side in the figure) of theprojection 17 is formed into an approximately circular-arc shape inlongitudinal cross-section, and the welded portion 14 is located on themaximum outer-diameter portion of the projection 17. This isadvantageous in enlarging an area of the welded surface of the weldedportion 14, thereby obtaining a higher joining strength (weldingstrength).

According to the present invention, the shape of the projection 17 andthe position of the welded portion 14 relative to the projection 17 arenot limited to those described above. For example, each of one side andthe other side of the projection 17 may be formed into a non-circular(non-circular arc) such as a trapezoidal or triangular shape inlongitudinal cross-section. The proximal side and the distal side of theprojection 17 may be formed into shapes asymmetric to each other withrespect to the welded surface (connection end face 21, 31) of the weldedportion 14. The axial position of the welded surface of the weldedportion 14 relative to the projection 17 is not necessarily located atthe central portion as shown in FIGS. 4, 5, and 7 but may be located ata position offset to the proximal side (second wire 3 side) or on thedistal side (first wire 2 side). With this configuration, it is possibleto prevent or relieve stress concentration at the welded portion 14, andhence to more certainly prevent breakage of the welded portion 14 due tostress concentration at the welded portion 14 when a torsional torque orpushing force is applied from the second wire 3 to the first wire 2.

The cover layer 5 covering the projection 17 may be configured as thereinforcing layer described in the embodiment shown in FIG. 6. In thecase of covering the projection 17 with a metal material, the joiningstrength of the projection 17 can be improved. For example, by insertinga relatively thin metal tube to a portion near the projection 17 andapplying a pressure to the metal tube from external, the cover layer 5strongly adhering on the projection 17 can be formed.

FIGS. 8 and 9 are views showing the operational state of the guide wire1 of the present invention during use in the PTCA process.

In FIGS. 8 and 9, reference numeral 40 denotes an aortic arch, 50 is aright coronary artery of a heart, 60 is an ostium of the right coronaryartery 50, and 70 is a target angiostenosis portion. Further, referencenumeral 30 denotes a guiding catheter for certainly guiding the guidewire 1 from an arteria fermoralis into the right coronary artery 50, and20 is a balloon catheter having at its distal end an expandable andcontractible balloon 201 for dilating the target angiostenosis portion70.

As shown in FIG. 8, the guide wire 1 is moved in such a manner that thedistal end thereof projecting from the distal end of the guidingcatheter 30 is inserted in the right coronary artery 50 through theostium 60 of the right coronary artery 50. The guide wire 1 is furtheradvanced, and is stopped when the distal end thereof passes the targetangiostenosis portion 70 in the right coronary artery 50. In this state,an advance path of the balloon catheter 20 is ensured. At this time, thewelded portion 14 of the guide wire 1 is located in the living body,more specifically, in the vicinity of the distal portion of the aorticarch 40.

As shown in FIG. 9, the balloon catheter 20 is inserted around the guidewire 1 from the proximal side of the guide wire 1. The balloon catheter20 is then advanced in such a manner that the distal end thereofprojects from the distal end of the guiding catheter 30, goes aheadalong the guide wire 1, and enters the right coronary artery 50 from theostium 60 of the right coronary artery 50. The balloon catheter 20 isstopped when the balloon 201 reaches a position corresponding to that ofthe target angiostenosis portion 70.

A fluid for inflating the balloon 201 is injected in the ballooncatheter 20 from the proximal side of the balloon catheter 20, toinflate the balloon 201, thereby dilating the target angiostenosisportion 70. As a result, deposits such as cholesterol adhering on thearterial wall of the target angiostenosis portion 70 are physicallycompressed against the arterial wall, to eliminate blocking of bloodflow.

In the above-described embodiments, each of the composing elements ofthe guide wire may be replaced with a composing element having any otherconfiguration exhibiting the similar effect, and may be provided withany other additional element.

While the preferred embodiments of the present invention have beendescribed using specific terms, such description is for illustrativepurposes only, and it is to be understood that changes and variationsmay be made without departing from the spirit or scope of the followingclaims.

1. A method of manufacturing a guide wire comprising: providing a firstwire and a second wire, the first wire and the second wire being madefrom different materials; welding the first wire to the second wire at awelded portion; and coating an outer periphery of the welded portionwith a polymer cover layer while the welded portion is not heated. 2.The method according to claim 1, wherein the first wire and the secondwire each possess an end face, and the end face of the first wire andthe end face of the second wire are welded to one another at the weldedportion so that the first and second wires do not axially overlap oneanother.
 3. The method according to claim 2, wherein the end face of thefirst wire and the end face of the second wire are each perpendicular toan axial direction of the first and second wires, and the weldingbetween the first and second end faces is performed by a butt resistancewelding process.
 4. The method according to claim 2, wherein the endface of the first wire and the end face of the second wire are areformed into a recessed and raised shape, respectively.
 5. The methodaccording to claim 1, wherein a proximal-side cover layer is disposed ona proximal side from the polymer cover layer without an axial gapbetween the polymer cover layer and the proximal-side cover layer; thepolymer cover layer and the proximal-side cover layer do not axiallyoverlap one another; a distal-side cover layer is disposed on the distalside from the polymer cover layer without an axial gap between thepolymer cover layer and the distal-side cover layer; and the polymercover layer and the distal-side cover layer do not axially overlap oneanother.
 6. The method according to claim 5, wherein at least one of thefirst wire and the second wire is directly heated to form theproximal-side cover layer and the distal-side cover layer.
 7. The methodaccording to claim 5, wherein the distal-side cover layer is made from amaterial that reduces friction of the distal-side cover layer.
 8. Themethod according to claim 5, wherein the distal-side cover layer is madefrom a fluorocarbon resin or hydrophilic material.
 9. The methodaccording to claim 5, wherein an average thickness of the distal-sidecover layer is in a range of 1 to 20 μm.
 10. The method according toclaim 5, wherein the distal-side cover layer is separate from thepolymer cover layer, with a joint between a proximal end of thedistal-side cover layer and a distal end of the polymer cover layer, thejoint being positioned about a tapered portion of the first wire. 11.The method according to claim 1, wherein the polymer cover layer is madefrom a fluorocarbon resin or hydrophilic material.
 12. The methodaccording to claim 1, wherein the polymer cover layer is made from asilicone resin.
 13. The method according to claim 1, wherein a thicknessof the polymer cover layer is within the range of 1 to 2 μm and isuniform throughout the polymer cover layer.
 14. The method according toclaim 1, wherein a thickness of the polymer cover layer is uniform. 15.The method according to claim 1, wherein the polymer cover layer extendsacross the welded portion and has a thickness that is uniform from aproximal end of the welded portion to a distal end of the weldedportion.
 16. The method according to claim 1, wherein the first wire ismade from a superelastic alloy and the second wire is made fromstainless steel.
 17. The method according to claim 1, wherein the secondwire is made from a Co-based alloy and the Co-based alloy is a Co—Ni—Cralloy.
 18. The method according to claim 1, wherein the second wire ismade from a material having an elastic modulus larger than that of thefirst wire.
 19. The method according to claim 1, wherein the polymercover layer is made from a reaction-curing type of resin material or acomposite material thereof, and a formation of the polymer cover layeris performed at room temperature.
 20. The method according to claim 1,wherein an entire outer surface of the polymer cover layer is devoid ofgrooves.